The invention relates to an electrochemical accumulator (referred to for short in the following text as an accumulator). The invention also relates to a vehicle having an electrochemical accumulator.
High-power accumulators with high energy densities in the electrochemical cells are used in particular in hybrid vehicles (for example a vehicle with an accumulator and a fuel cell) and in electrical vehicles (for example electrical road vehicles).
The high energy densities lead to a large amount of heat being developed. In order to maintain the performance of the accumulators and allow them to guarantee a wide operating window (which is governed, for example, by the outside temperatures), effective cooling is needed for the accumulators.
Effective and furthermore cost-effective cooling of the accumulators is achieved by air cooling. For air cooling, cooling air channels are provided between the individual cells in the accumulator, through which cooling air channel cooling air is passed with the aid of a fan.
It is known for the cooling air which is available for cooling of the accumulator to be taken from the air-conditioned passenger compartment. Particularly in countries with high annual average temperatures, the use of the outside air is ineffective. Furthermore, when using the outside air, filter systems are required in order to remove contamination (for example sand) from the cooling air before the cooling air is passed through the accumulator.
This increases the costs of these cooling systems.
High-power accumulators with high energy densities require not only effective cooling but also a safety system to protect the accumulator against an excessive gas pressure in the cells. The excessive gas pressure in the cells can lead to sudden reactions within the cells, and to ignition of the cells. This can result in people being injured, and the environment being damaged.
By way of example, bursting openings (weak points) are integrated in the cell walls as a safety system against excessive gas pressure in the cells. These weak points can prevent an explosion in the cells in the event of damage (for example a short circuit, overcharging, mishandling) which is associated with excessive gas pressure in the cells. The cells open in defined conditions (a specific gas pressure in the cells) and in this case dissipate the excessive gas pressure that has occurred within the cells. The gas which escapes through the opened weak points in this case leaves the accumulator via the cooling air channels. The gases emerging from the cells are hazardous to health.
One object of the present invention is to provide a high-performance and safe electrochemical accumulator, which can be used in particular in hybrid vehicles and electrical vehicles. A further object of the present invention is to provide a vehicle having a high-power electrochemical accumulator which is safe for the user.